EFFECS OF CLOSURE STRESS ON FRACTURE MORPHOLOGY AND MULTI-PHASE FLOW IN SHEAR FRACTURED BEREA SANDSTONE
Open Access
- Author:
- Al Enezi, Sultan Mohammad
- Graduate Program:
- Petroleum and Natural Gas Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 02, 2009
- Committee Members:
- Phillip Michael Halleck, Dissertation Advisor/Co-Advisor
Phillip Michael Halleck, Committee Chair/Co-Chair
Abraham Grader, Committee Member
Derek Elsworth, Committee Member
Zuleima T Karpyn, Committee Member
Demian Saffer, Committee Member - Keywords:
- shear fracture
fluid flow - Abstract:
- Understanding the mechanical properties of fractures and how fractures affect single and multi-phase flow behavior is very important, not only in petroleum reservoirs but also in many other fields. Multi-phase flow behavior in shear fractures is not fully understood. This study focuses, on fracture morphology and hydraulic behavior of a shear fracture, along with the effects of closure stress. Morphology of the shear fracture and the effects of increasing the closure stress on fracture properties were studied under dry condition using high resolution Micro-Computed Tomography (MCT). Fracture properties such as average aperture and asperity ratio are highly affected by increasing the closure stress. Two multi-phase flow experiments were conducted under two different closure stresses. Full scans were acquired at different saturation conditions at both closure stresses. High effective oil permeability combined with low Swirr in the fracture and high Swirr in the matrix, indicates that the fracture is acting as an oil conduct. Increasing the closure stress has no significant effect on the fluid distributions inside the fracture and on effective permeabilities; the same behavior was observed at both closure stresses. Fluid distributions at all saturation conditions and at both closure stresses confirm that oil occupies the large apertures; and cannot be displaced out of the fracture and force the water to flow in the matrix and the small apertures, thus yielding very low water relative permeabilities at Sor. The saturations in the matrix adjacent to the fracture were calculated and compared to the saturations in the fracture. Increasing water saturation was observed going from the fracture into the wall and further matrix at both Swirr and Sor conditions.